moving your leaf srping underneath the frame rail!

[Stoney]

i wanted to know if anyone had ever tried moving there leaf srping underneath the frame rail before? i am thinkin about using stock or almost stock leaf srping and moving them underneath the frame rail, which would create more flex and possiblity of a bigger lift!!

i am just wondering if anyone has ever seen this done or if i am going to be the first?!!?!?!?!

stoney

 

[TC]

Do it! I've been thinking about this lately also, tired sagging lift springs at $400+ bucks a set that don't last. I'm going to look at longer springs, possibly the 80's rear GM springs that are popular on lifted Toyota's. So far it's just been bouncing around in my head, I haven't even touched my XJ in weeks. Hopefully I'll start on this sometime next month. Keep us posted. TC

 

[Bender]

I've toyed with this idea for a while and came up with a few things.

Just by moving the mounting points under the frame rails you'll gain a good 3" of lift with your same springs. Also by moving the leaf spring mounting points inward on the axles you will increase the leverage applied to them by the wheels causing more sway on the road. Significantly more I'd imagine seeing as you wouldn't need as stiff of spring for the same lift. This will also net easier articulation on the trails. Also, if you chance that isn't enough flex for you a buggy leaf setup would be quite easy.... some have done this already I believe.

The main drawbacks of this are the time and re-inforcing required. At foward spring mount you'd need to reinforce the framerail to handle that extra leverage. You'd also need to re-locate your axle perches so lots of grinding, cutting, and welding is in order. The rear shock mounts will also need to be moved as they are currently located on the axle right were the spring perches will need to go. Also, if you have the stock gas tank skid it will have to go as it mounts directly to the frame rail where the shackle mounts will now be. You'd also need to find a way to securely mount and aftermarket bumpers, trailer hitches etc.

 

[Slip Kid]

I think it's a good idea as long as it's reinforced. It has the potential to be much stronger than stock. The stock spring hangers are a weak point, and will eventually rust and the springs shoot up through your floor. I've toyed with the idea before, but I will probably end up just reinforcing the existing mounts.

 

[CheapXJ]

just looking at it...

where are you gonna put your hitch/gas tank skid of ya have them?

I'm having trouble with exhaust routing back there with all that junk and I cannot just put a turn down on the exhaust due to legal issues... (stupid PA insepctions)

It would be hella sweet to do that though. perhaps a bolt on hanger mated to a reinforced plate in the rear so it would accept a YJ type shackle

 

[Cresso]

I've seen it done - I'm trying to find pics now. It resulted in exactly what has been stated here - more flex, more body roll. I believe the one I saw had the gas tank swapped out for a fuel cell that had been moved up into the rear storage area. I can't recall exactly, but I think the shackes were mounted straight to a custom bumper, negating the need to remove the stock mounts and fab new mounts through the frame. I don't remember if this person used longer springs or just moved the axle back to account for the farther back shackle.

 

[JeepFreak21]

I've seen it done - I'm trying to find pics now. It resulted in exactly what has been stated here - more flex, more body roll. I believe the one I saw had the gas tank swapped out for a fuel cell that had been moved up into the rear storage area. I can't recall exactly, but I think the shackes were mounted straight to a custom bumper, negating the need to remove the stock mounts and fab new mounts through the frame. I don't remember if this person used longer springs or just moved the axle back to account for the farther back shackle.

That's what I'm considering doing...
I figured, since I have a hitch, I'll make a custom bumper and mount the spring hanger to that.... trouble with that is, if you use your current springs, it'll move the axel back a good 3 inches... then you have to worry about hitting the gas tank w/ the diff when you flex.

 

[TC]

I think a better way would be to retain the same spring perch location as stock, that way you don't have to change spring pads, rear shackles, or anything between the two springs. The way to do this wouldn't be that difficult, you could use the stock front hanger as one part of the attaching point with a plate or box along side the "frame rail" ahead of the original hanger. This would strengthen the whole area considerably. I'd prefer this over narrowing the mounting locations of the perches for stability reasons and simplicity. If the replacement springs are exceptionally long you could rework the shackle mounts in the rear fairly easily. TC

 

[Matt]

I did it - I will elaborate more tomorrow but really the only issue is the gas tank clearence - and yes I made it work with the 20gal tank and a cut down OEM skid still attached...

I made a plate that connected to the old welded nut on the frame for the OEM position and completed one side of the hanger (other side is 4" angle iron welded to the underside of the frame)
Matt

Buggy leaf and all...

 

[Stoney]

hey matt is it drivable on the road! cuz this is my daily driver!!

but i am also a very good driver!!!

stoney

 

[CRASH]

but i am also a very good driver!!!

Just stay out of Stoney's way at any gas stations......

Is it just me, or does the thought of leaf spring hangers dangling below the frame rail sound like a recipe for major hangups in the deep rocks?

CRASH

 

[Ed A. Stevens]

Bill Ansell moved the leafs under the frame, but changed back after a month or two. The flex was great, but the roll stiffness was too soft for his use, and he could not get a good shock angle to provide adequate dampening. The sidehill stability was poor.

The factory mounts can be built-up as well, to gain the same lift, leaving the wide leaf spacing.

The shackle box cover and tab addition to relocate the rear mount is now on more than a few XJ's.

Relocating the front mount with the same style of cap and bracket (using 2x3 box tubing) has the advantage of reducing the potential for suspension jacking, in additon to the raw lift height gain.

The drawback of leaf mount relocation is reduced ground clearance, but the close proximity of the relocated mount to the radius of a 33 or 35-inch tire makes them hard to hit. With the larger tires the loss of clearance is less critical at the mounts, much like LCA drop brackets on the front suspension.

The other issue is driveline length and driveshaft spline plunge travel. Moving the front leaf mount centerline height further away (lower than) from the foward u-joint pivot centerline height will alter the relationship between the t-case and pinion throughout the travel range. You will need a longer draveshaft with a greater sline travel range (although most of the aftermarket SYE shafts should not have a problem).

 

[ashmanjeepxj]

I did it - I will elaborate more tomorrow but really the only issue is the gas tank clearence - and yes I made it work with the 20gal tank and a cut down OEM skid still attached...

I made a plate that connected to the old welded nut on the frame for the OEM position and completed one side of the hanger (other side is 4" angle iron welded to the underside of the frame)
Matt

Buggy leaf and all...

I wana see some more pics matt!!

Im not a fan of moving the perches in-board.
Stability was brought up, and I agree, it would be soft, flexy but not stable.

Matt, this is my 3/4elip plan.. Ill be running my d70 rear with the perches welded to the factory cherokee leaf perch width.

I will use a factory Xj no lift leaf back for the 1/2 elip adn use two leafs out of an F350 pack I have for the top 1/4elip.

I will flip the XJ pack so the longside goes to the front. I dont want to stretch my wheel base that much so Ill make new mounts further forward then stock.

I plan to get 8.5in of lift from the shackle and the f350 leafs.
I want the upper 1/4elip to not be fully compressed at ride height.
Have a fixed frame end mount like yours to limit the down travel unlike the double shackles.

yours looks like the top single leaf 1/4elip has no up travel compression.

what do you think?

Yes I know my described set up will cuase some big anti squat due to the angle on the lower 1/2elip but I have the stuff and want to give it a try. Ill later on build a link set up to fix the anti-squat and eventually replace the "free" leafs with some coilovers..

I have a 2dr and will severly trim instead of increasing the wheel base. I have some skinny bucket seats to replace the back seat so I can extend my wheel wells forward to where the bench used to go. Gas tank I want to move up anyways.

for now just fitting 37s and keeping it full width.

What do you think of my 3/4elip plan?

 

[TC]

I don't think ground clearance will be much of an issue, this type of mod only makes sense for those with the larger tires, plus thats one more reason to maintain full width...tires closer in line to the mounts. TC

 

[CRASH]

I don't think ground clearance will be much of an issue, this type of mod only makes sense for those with the larger tires,

How does this logic work? You get tires that are 6" larger in diameter, thereby increasing ground clearance under the frame rails by 3", only to eat up that three inches with a spring mount?

I don't get it...... :huh:

CRASH

 

[Ed A. Stevens]

How does this logic work? You get tires that are 6" larger in diameter, thereby increasing ground clearance under the frame rails by 3", only to eat up that three inches with a spring mount?

I don't get it...... :huh:

CRASH

How far forward, from the leading edge of the tire radius, is the spring mount with the larger tire? Is there more, or less, room to hang the mount now hanging under the frame rail elevation on a rock before the tire radius has you climbing the obsticle?

The mount may be the same height off the ground (three-inch mount and three-inch taller tire), but it's also three inches closer to the tire's leading edge.

 

[ashmanjeepxj]

How does this logic work? You get tires that are 6" larger in diameter, thereby increasing ground clearance under the frame rails by 3", only to eat up that three inches with a spring mount?

I don't get it...... :huh:

CRASH

The mount is frame height not axle height.

Axle height ground clearance is like you said increased by every inch in radius.

but the leafs are mounted to the frame so there clearance depends on amount of lift and tire size..

so to add a 6in taller tire, a 37 in my case you also add 8in of lift. so the fame is 11in taller then stock so the 3in drop is not "that" bad.

that was what TC Member was saying...

 

[Stoney]

hey crash not too argue too much but u would have the same amount of ground clearance if u use the same leaf springs but the frame will be taller!! also why would u do long arms or anything else to lower the grand clearance!! again jsut stating an idea!

stoney

 

[CRASH]

My point is that there are so many negatives to this mod, ground clearance issues being one of them, that I can't imagine why you would want to do it.

The roll axis is going to be horrible, which is going to make steep, off-camber climbs feel really scary, so you'll compensate by adding leafs, which will make the ride horrible and unbalance the spring rates front to back.

Stoney, don't you remember us always making fun of CJ guys and their "covered wagon" rigs? One of the reasons is they are always getting hung on their leaf spring mounts in the rear on those ledgy, technical climbs. Just as they get their back tires to start crawling up an obstacle, they'll hang up on that mount. It's damn near a guarantee. Despite what Ed says, about the hangers relationship to tire size, those mounts are very vulnerable.

To each his own, and it should make for an entertaining experiment. I say go for it, you guys always provide good comic relief on the trail, and I'd hate to take that away from you.....

CRASH

 

[JnJ]

Ya, some of the CJ guys are getting smart and sinking their mounts into the frame. We already have that..kind of..